What in vitro diagnostics are
In vitro diagnostics (IVD) are medical tests performed on samples taken from the body — blood, urine, tissue — and analysed in a lab or device, rather than tests done directly on the patient. The category spans everything from a cholesterol panel to advanced molecular assays.
Why it matters for longevity
Most longevity biomarker testing is IVD: serology, metabolomics, microbiome metagenomics and methylation-based epigenetic clocks all rely on analysing a sample outside the body. The quality, standardisation and validation of the underlying IVD determine how much a result can be trusted.
What the evidence shows
Regulated IVDs used in mainstream medicine are rigorously validated. The longevity market, however, includes many lab-developed and consumer tests with uneven validation, so the same biomarker can differ meaningfully between providers.
Bottom line
The reliability of any biomarker result rests on the IVD behind it — favour standardised, validated assays and be cautious with novel consumer panels.